Influence of slip on the dynamics of two-dimensional wakes

TL;DR

This study numerically investigates how slip boundary conditions affect the wake dynamics behind a circular cylinder, revealing delays in vortex shedding, reductions in drag and vorticity, and increased shedding frequency, with implications for passive surface property inference.

Contribution

The paper introduces a detailed numerical analysis of slip effects on wake transition and vortex shedding, highlighting new insights into flow control and surface property estimation.

Findings

Slip delays recirculation and vortex shedding onset.

Slip reduces drag and wake vorticity.

Slip increases vortex shedding frequency.

Abstract

We study numerically the two-dimensional flow past a circular cylinder as a prototypical transitional flow, and investigate the influence of a generic slip boundary condition on the wake dynamics. We show that slip significantly delays the onset of recirculation and shedding in the wake behind the cylinder. As expected, the drag on the cylinder decreases with slip, with an increased drag sensitivity for large Reynolds numbers. We also show that past the critical shedding Reynolds number, slip decreases the vorticity intensity in the wake, as well as the lift forces on the cylinder, but increases the shedding frequency. We further provide evidence that the shedding transition can be interpreted as a critical accumulation of surface vorticity, similarly to related studies on wake instability of axisymmetric bodies. Finally, we propose that our results could be used as a passive method to infer the effective friction properties of slipping surfaces.